negotiations

Senate Democrats said Tuesday that the GOP letter about nuclear talks with Iran undercuts the U.S. at the negotiating table and threatens to torpedo bipartisanship on Capitol Hill when it comes to the delicate issue of preventing a nuclear-armed Iran.

Secretary of State John Kerry warned Congress Wednesday against scuttling a historic opportunity for a nuclear pact with Iran by pressing ahead with new sanctions while international negotiators seek to prevent Tehran from being able to assemble an atomic weapons arsenal.

President Barack Obama is taking his case for avoiding a potentially unsettling “fiscal cliff” to the Philadelphia suburbs, employing campaign-style tactics in hopes of mobilizing public support. The trip comes amid signs of impatience in the negotiations between Republican leaders and the White House.